Satellites of Milky Way- and M31-like galaxies with TNG50: quenched fractions, gas content, and star formation histories

We analyse the quenched fractions, gas content, and star formation histories of ~1200 satellite galaxies with $M_* \geq 5 \times 10^6~{\rm M}_\odot$ around 198 Milky Way- (MW) Andromeda-like (M31) hosts in TNG50, highest-resolution simulation IllustrisTNG. Satellite fractions are larger for smaller masses, distances to their host galaxy, more massive M31-like compared MW-like hosts. As satellites cross host's virial radius, content drops: most within 300 kpc lack detectable reservoirs at $z=0$, unless they like Magellanic Clouds M32. Nevertheless, stellar assembly exhibits a large degree diversity. On average, cumulative extended brighter, later infall, those less Based on these relationships, we can even infer infall periods observedMWand M31 dwarfs: e.g. 0-4 Gyr ago Leo I, 4-8 0-2 M32 IC 10, respectively. Ram pressure stripping (in combination tidal stripping) deprives TNG50 ultimately quenches formation, though only few per cent present-day MW/M31-like appear as jellyfish. The typical time since quenching currently is $6.9^{+2.5}_{-3.3}~{\rm Gyr}$ ago. results consistent observed MW satellites, however, SAGA survey \sim 10^{8-9}~{\rm exhibit lower than other, analogues.